1. Field of the Invention
The present invention relates to an image recording apparatus such as an ink-jet recording apparatus configured to perform image recording by ejecting ink droplets from a recording head onto a recording medium. More particularly, the present invention relates to an image recording apparatus including a cap which covers ink-ejection openings of the recording head and which is slidable between a position at which the cap covers the ink-ejection openings and a position at which the cap is distant from the ink-ejection openings, in order to perform a purging operation in which the ink is sucked and discharged from the recording head by a sucking pump.
2. Description of the Related Art
There is conventionally known an apparatus configured to record various images such as a character, a picture, and a wiring pattern by ejecting liquid droplets. For example, there is known an image recording apparatus configured to record an image on a sheet by ejecting ink on the basis of input signals. This type of the image recording apparatus is generally referred to as an “ink-jet printer”. The image recording of the ink-jet printer is performed by selective ejection of the ink from ink-ejection openings of a recording head.
In the recording head, there may arise a case of generation of air bubbles and/or clogging of foreign materials in ink passages respectively leading to the ink-ejection openings. These generation and clogging may adversely affect the ejection of the ink droplets from the recording head. In order to prevent or recover this adverse affection, there is known a technique for removing the air bubbles and the foreign materials from the ink-ejection openings of the recording head. This technique is generally referred to as “purging”. This purging is performed by a maintenance unit. The maintenance unit includes: a cap for covering the ink-ejection openings of the recording head; a pump for absorbing the ink by reducing a pressure in the cap; a waste ink tank for storing the absorbed ink; a tube connecting the pump and the waste ink tank; and so on.
When the image recording is performed on the sheet, the recording head is movable in a direction perpendicular to a sheet feeding direction in which the sheet is fed. In this time, the cap is distant from the ink-ejection openings of the recording head. When the purging is performed, the ink-ejection openings of the recording head are covered with the cap, so that an airtight space is formed between the recording head and the cap. When the pump is driven in this state, the ink is absorbed. As thus described, the ink-jet printer includes a cap lifting mechanism which causes the cap to slide between a position at which the cap covers the ink-ejection openings by closely contacting the recording head and a position at which the cap is distant from the recording head. A friction clutch mechanism may be used as a means for the sliding of the cap.
For example, there is known an ink-jet printer in which a gear driven by a drive force transmitted from a motor is connected via only a friction clutch mechanism to a wiping means for wiping ink attached to a nozzle surface of a recording head, and the wiping means is rotated upward or downward by the drive force transmitted from the motor.
In this ink-jet printer, the friction clutch mechanism includes a tooth chipped gear, a normal gear, and a compression spring for pressing the gears to each other. The tooth chipped gear is formed integrally with a shaft supporting portion of the wiping means. The tooth chipped gear and the normal gear are meshed with a gear of a cam having a gear (hereinafter referred to as a “cam gear”) to which the drive force is transmitted from the motor. However, a toothless portion of the tooth chipped gear and the cam gear are not meshed with each other.
In a state in which the cam gear is held in meshing engagement only with the normal gear and is not held in meshing engagement with the tooth chipped gear, the drive force from the cam gear is transmitted only to the normal gear. In this case, the drive force is not transmitted to the wiping means, so that the wiping means is not rotated. However, when the tooth chipped gear is rotated with the rotation of the normal gear by the friction clutch mechanism, the cam gear is meshed also with the tooth chipped gear. Thus, the drive force from the cam gear is transmitted also to the tooth chipped gear. As a result, the drive force is transmitted to the wiping means, so that the wiping means is rotated.